With progressive development of the display technique, more and more people begin to focus on the Organic Light Emitting Diode (OLED) display element with better display capability. As a current-type light-emitting element, the OLED display element is increasingly applied to a high performance display field due to its features such as self-luminescence, rapid response, wide view angle, and the capability of being manufactured on a flexible substrate. An OLED display element can be classified into a Passive Matrix Driving OLED (PMOLED) display element or an Active Matrix Driving OLED (AMOLED) display element. As the size of the display apparatus is increased, in the conventional PMOLED display, the driving time for a single pixel is required to be reduced, and thus the transient current is required to be increased, which causes a dramatic increasing of the power consumption. In the technique of AMOLED, such issues can be addressed well since the current is input to each of OLEDs via the Thin Film Transistor (TFT) switching circuit when scanning is performed row by row.
In the existing AMOLED panel, most thin film transistor switching circuits adopt Low-temperature poly-silicon thin film transistors (LTPS TFT) or oxide thin film transistors (Oxide TFT). Compared to the general amorphous silicon thin film transistor (amorphous-Si TFT), LTPS TFT and Oxide TFT have higher mobility and more stable characteristics, and thus they are more suitable for being applied into an AMOLED display. However, due to limitations of the crystallization process and the manufacture level, the non-uniformity occurs in the electrical parameters of the TFT switching circuit which is manufactured on a glass substrate with a large size, such as threshold voltage, mobility and the like, so that the shift of the threshold voltage varies in respective TFTs, which results in a current difference and a luminance difference among respective OLED display elements; such differences are perceived by human eyes, and thus the issue of non-uniform display effect arises among respective pixels. Even if a grey voltage of a same grey level is applied to all of the pixels, the issue of non-uniform luminance arises among the pixels due to the non-uniformity among respective pixels, thus deteriorating the display quality and affecting user's experience on use severely.